1. Field of the Invention
The present invention relates to an organic electroluminescent device wherein a yield is enhanced, the permeation of moisture from the outside can be inhibited, the life is extended and the quality of display is enhanced.
2. Description of the Related Art
It is widely recognized that in today's advanced information society, a display which is an information terminal takes an important position of a man-machine interface.
Generally, it is CRT, that is, a conventional type cathode-ray tube that is used for a display, particularly a display for a personal computer, which has been recently remarkably popularized. In the meantime, for a personal computer, recently, the demand of a portable terminal has also increased.
For a purpose of using the above-mentioned portable terminal, conventional type CRT which is heavy and requires large space is not suitable and in place of it, a thin, light and flat-type display that further enables large capacity display has attracted attention.
The above-mentioned flat-type display includes many types such as a plasma display (PDP), a liquid crystal display (LCD), a vacuum fluorescent character display tube (VFD) and an electroluminescent (EL) display and has been variously developed in accordance with each property. Above all, an electroluminescent device has recently actively developed for a mobile telephone which is a mobile terminal.
An electroluminescent device is formed by sandwiching an organic luminescent layer between a transparent electrode and a back electrode. A hole and an electron are injected into the organic luminescent layer by applying voltage between both electrodes. Then, a fluorescent substance in the organic luminescent layer is excited by energy generated in the recombination of these and light radiated when the excited fluorescent substance returns to a ground state is utilized. For the above-mentioned transparent electrode of such an electroluminescent device, a transparent conductive thin film such as indium-tin oxide (ITO) is used to transmit emission from the organic luminescent layer.
In the organic luminescent layer of the electroluminescent device, the deterioration of a property by moisture is remarkable, for example, when the organic luminescent layer comes in contact with moisture in air, chemical change occurs, the quality of display is deteriorated and the life of emission is reduced. Therefore, in a conventional type electroluminescent device, as disclosed in Japanese published unexamined patent application No. 2000-21566, an organic luminescent device is protected by bonding a sealing member 14 to a transparent electrode 12 provided on a transparent substrate 11 or an auxiliary electrode 13 provided on the transparent electrode by an adhesive 15 and holding sealed space in inert atmosphere (see FIG. 1).
Also, in Japanese published unexamined patent application No. Hei 11-85057, a color liquid crystal panel in which a part of an electrode line 21 crossing the sealing member 23 is a transparent conductive layer 22 and a color liquid crystal panel in which a part of an electrode line 31 crossing the sealing member 33 has an opening 34 and a transparent conductive layer 32 is laminated in an area including the opening are disclosed (see FIGS. 2 and 3).
According to an electroluminescent device disclosed in Japanese published unexamined patent application No. 2000-21566, the enhancement of the quality of display is recognized to some extent, however, when ultraviolet rays are irradiated from the side of the outside face of a transparent substrate and an adhesive is cured, an uncured part may be left in a bonded part because an auxiliary electrode is made of opaque metallic material and a problem that moisture easily permeates cannot be avoided.
In the meantime, according to the color liquid crystal panel disclosed in Japanese published unexamined patent application No. Hei 11-85057 and devised in the part of the electrode line crossing the sealing member, the enhancement of the adhesion property to some extent is recognized, however, for example, there are problems that in the color liquid crystal panel shown in FIG. 2, as only the transparent electrode is independently formed in the sealing part, resistance increases and in the one shown in FIG. 3, as there is a part in which the metal electrode line is continuous longitudinally in the sealing part, an adhesion property between the adhesive and the metal becomes weak, moisture easily permeates and the life is reduced.